A petition calling on Work and Pensions Secretary Iain Duncan Smith to live off £53 a week has been handed in to his office - as major changes to disability benefits are rolled out.

New claimants in parts of northern England will now receive Personal Independence Payments (PIP) in place of the old Disability Living Allowance (DLA), which critics say will leave many worse off.

The new system which includes face-to-face assessments and regular reviews will take at least two years to roll out across the country.

Image:Iain Duncan Smith: Old system is "ridiculous"

Steven Sumpter from Worcestershire, who suffers from ME and diabetes so finds walking painful, told Sky News he was worried about the future.

Previously, to get disability benefit he had to prove he was unable to walk 50m, but that will be changed to 20m.

Video:Impact Of Welfare Reforms

He said he fears in the future he will lose half of the money he receives and the subsidised car he relies on.

"It means every single trip to the shops and the doctor will turn into maybe three hours of effort and that will leave me in bed, exhausted and in pain for days afterwards," he said.

The Government insists DLA was outdated and the changes mean those who really need support will now receive it.

Mr Duncan Smith has described the previous system as "ridiculous".

"We've seen a rise in the run-up to PIP. And you know why? They know PIP has a health check. They want to get in early, get ahead of it. It's a case of 'get your claim in early'," he told the Daily Mail.

He added that rigorous new health checks for claimants were "common sense".

Some charities have already expressed concerns that it will mean 600,000 people miss out on support.

Chief Executive of Scope, Richard Hawkes, admitted changes were needed but claimed the Government was motivated by cost cutting.

"The Government has already announced how much the Disability Living Allowance budget is going to be reduced, they've already announced how many people are going to lose DLA and they're introducing a test which is going to provide them with the results they want to reduce those costs.

It’' not right, it's not fair," he told Sky News.

PIP will initially be introduced for new claimants in northwest England, Cumbria, Cheshire, northeast England and Merseyside.

Meanwhile, welfare reform campaigners have delivered a petition bearing 450,000 names to the Department of Work and Pensions.

Mr Duncan Smith was challenged to live on £53 a week after a market trader on a radio show said that was all he had to live on despite working 50 to 70 hours a week.

Asked whether he could live on £53 a week, the former army officer, who now earns around £1,600-a-week after tax replied: "If I had to I would."

The Cabinet minister has since dismissed the campaign as a "complete stunt".

Musician and part-time shop worker Dominic Aversano, who started the petition on campaigning website Change.org, said: "I don't think Mr Duncan Smith has a choice about whether to listen to the petition because so many people have signed it.

"I think it has changed the debate around welfare cuts. I was surprised because I didn't think we would have such a large response. I am delighted."

As well as the Personal Independence Payments, other reforms, including a below-inflation 1% cap on working-age benefits and tax credit rises for three years, have already come into force.

Around 660,000 social housing tenants deemed to have a spare room will lose an average of £14-a-week in what critics have dubbed a "bedroom tax".

Trials of a £500-a-week cap on household benefits are also due to begin in four London boroughs.

Chancellor George Osborne insisted on Sunday that the public was behind his changes to the benefits system.

Mr Osborne also said he felt "angry" that too much money was being "spent in the wrong way in our welfare system".